So I ended up ordering some more set screws and other pieces I thought I could use but ended up buying most of the pieces from Home Depot. End result? Used a double set screw for each location with locktite red, the 2nd screw to keep the first in place. Had to adjust the tire and take the chain off to work on it but that wasn’t too bad. Also added a collar lock tight against the sprocket to keep the sprocket from moving should the key find someway out again, which may be unlikely as I added an end cap to the shaft as it is a threaded 7/16-20 shaft. The concern with the shaft cap is that is clockwise to the view while the rotation is counterclockwise so it does have the potential to unscrew despite the additional locktite on it.